Impaired mitochondrial oxidative phosphorylation induces CD8⁺ T cell exhaustion

CD8⁺ T cells play a crucial role in anti-tumor immunity, but their function can be impaired by exhaustion induced by prolonged antigen stimulation. Mitochondrial dysfunction, a hallmark of the tumor microenvironment (TME), has been linked to various pathologies, but its specific role in CD8⁺ T cell exhaustion remains underexplored. Here, we established an in vitro model of CD8⁺ T cell exhaustion by co-culturing OVA-specific OT1 CD8⁺ T cells with OVA-expressing MC38 tumor cells. Next, we investigated the impact of mitochondrial dysfunction on exhaustion using pharmacological inhibitors targeting the electron transport chain. The role of the mitochondrial complex I component NDUFA10 was further examined through genetic knockout in CD8⁺ T cells using CRISPR-Cas9. Inhibition of the mitochondrial electron transport chain significantly accelerated CD8⁺ T cell exhaustion in vitro. Knockout of NDUFA10 in CD8⁺ T cells led to enhanced tumor growth and increased exhaustion of tumor-infiltrating CD8⁺ T cells in a Rag1^-/- tumor-bearing transfer model. This study highlights the critical role of mitochondrial function in regulating CD8⁺ T cell exhaustion and anti-tumor activity, providing new insights into the metabolic underpinnings of immune dysfunction in cancer.